In a game device, a user's deck is formed by a plurality of battle cards or the like, and the game device allows the user to compete with an opponent based on a total value or the like of parameters such as attack strength, defense strength, and the like of the cards in the deck (for example, see JP 2008-220984A and JP 2000-325528A).
In a background game device, however, users may lose interest in the game. For example, in a background game device, a battle mode in which a user directly battles an opponent using the deck is adopted. In this battle mode, the victor is substantially determined by the strength of the cards or the deck. Therefore, a background game device is not necessarily highly strategic during a battle, and users may grow tired of battles.